Pulverizing mill



May 26, 1936.

E. G. BAILEY ET AL PULVERIZING MILL Filed May 21, V 1932 s Sheefs-Sheet 2 INVENTOR Err/22 6. Baz' Zey BY Perry P. Cassidy May 26, 1936. E. G. BAILEY ET AL 2,042,204

PULVERIZING MILL Filed May 21, 1932 5 Sheets-Sheet s g INVENTOR Ervin 'G. Bailey Perry E. Cassiay BY a! hMZ-{ardyrore 'I'I'ORNEY Patented May 26, 1936 UNITED STATES PATENT OFFICE PULVERIZING MILL Delaware Application May 21, 1932, Serial No. 612,758

16 Claims.

This invention relates to a pulverizer of that type in which rolling grinding elements are utilized to operate upon ores such as limestone, coal and the like.

The present application forms a continuation in part of our previously filed application Serial No. 575,453 filed November 16, 1931.

In pulverizers of the aforesaid character wherein feed is accomplished by gravity and centrifugal force it has been usual to make the rolling grinding elements, if arranged in concentric rows, all of one size, or if the elements of one row are larger than the other it has been customary to locate the rows in superposed relation.

The present invention, however, is a multi-stage pulverizer in which concentric rows of rolling grinding elements are incorporated, with those of larger size, and consequently greater weight,

on the inner row whereby the centrifugal effect is reduced to a minimum and the power required to drive the pulverizer is materially lessened.

Also, the material to be pulverized is introduced into the area within the inner row of larger grinding elements whereby the coarse heavy particles at the time of contacting the grinding elements have less centrifugal force and are consequently not carried through the interstices between the elements without being operated upon at all as might otherwise happen due to the fact that larger rolling elements, for instance of a type such as balls, have between them interstices of greater magnitude than does a row of smaller balls.

Furthermore the use of larger rolling grinding elements in the area of initial operation upon the material to be ground provides, at a particularly advantageous location, a type of element capable of most eflicient assimulation of the coarser particles of materials entering into the pulverizer, for the reason that larger balls, in their rolling effect, have the ability to take into the biting or pinching area a larger piece than is the case with smaller balls.

A further feature is, that with the arrangement of multiple rows of balls, with the smaller balls on the outside, there is produced a throttling effect retarding progress of the material through the pulverizer and thereby contributing to uni-- formity of feed and consequent uniformity of product.

In addition to the foregoing, the pulverizer embodies a ledge gap between rows of pulverizing units and formed by overlapping annular members, the arrangement of the members being such that they not only determine the feed through the gap but prevent the material from packing practical embodiment of the invention, in which,

Fig. 1 is a sectional side elevation of a pulverizing unit;

Fig. 2 is a fragmentary side elevation, enlarged, showing the ledge gap mechanism;

Fig. 3 is a view similar to Fig. 2 but showing more of an overlap to the ledge gap mechanism;

Fig. 4 is a top plan sectional view on the lin 4-4 of Fig. 1; and V Fig. 5 is a side elevation of a closed circuit mill system embodying the pulverizing unit of the present invention.

The pulverizer herein shown is of a type adapted to be incorporated in a closed circuit mill sys tem such as will be set forth later in the description.

The pulverizer unit comprises an enclosing casing II within which are housed several grinding rings, one of these designated at I2, is rotatable and is provided on its upper surface with concentric ball races l3 and I4 which will hereinafter be designated, respectively, as the inner and outer races.

The rolling grinding elements, which in this instance are in the form of sets of balls l5 and I6, are differently sized as to sets, those traveling the inner race l3 being larger, the purpose of which will presently appear. Opposite each set of ball grinding elements l5 and I6 is disposed a ring, the one indicated at ll cooperating with the inner row of balls l5 while the ring l8 engages the upper row I 6.

These grinding rings l1 and I8 are stationary, the ring l8 being held against rotation by the engagement of a lug l8 thereon with a lug ll on the casing ll, while the grinding ring I! is held against rotation by engagement of lugs l'l thereon with lugs l8 on. the grinding ring l8. The engagement of these lugs is inthe nature of a sliding relation with the result that these grinding rings l1 and I8 may have movement relative to each other and relative to the casing in a generally vertical direction. Each ring is held down upon the grinding balls or elements with which it co-acts by resilient compression means comprising a set of springs l9 acting upon the inner grinding ring 11, and a similar set of compression springs 20 acting upon the outer grinding ring l8. For adjustment of the com- 10 possible for a. hard or ungrindable piece of material to pass beneath one or more of the balls in one row without disturbing the operation of the balls in the other row.

Beneath the rotatable grinding ring l2 there 15 is provided another row or ring of grinding balls 2| which also are of smaller diameter than the balls of the inner row above described, and which are carried on a lower grinding ring 22 disposed in stationary relationship to the remainder of 20 the pulverizer and in such position that the total pressure of the springs l9 and .20 is transmitted thereto. through the medium of the upp grinding rings [1 and. I8 and their respective ball sets l and lfitogether with the rotatable grinding 25 ring l2 directly onto the lower row of balls, and thus the entire set-up or assembly is such that variation of the adjustment of the compression on springs 19 and 20 is carried out throughout the mill assembly and hence the pulverizer is 30; easily adjusted for pulverizing materials of varying hardness.

The intermediate rotating grinding ring [2 is driven by a vertical shaft 23 ,the thrust of which is carried by a thrust bearing 23'. The vertical 35 shaft 23 is fixedto a yoke 31 rotated therewith, and a lug or lugs 3'! on the yoke 31 engages with a lug or lugs l2 on the intermediate grinding ring l2 for the purpose of imparting rotation to the said ring l2, while yet permitting a relative 40- motion between the parts such as may adjust it to diiferent size particles beneath the balls 2| when the pulverizer is operating.

Bythis arrangement it will be observed that this rotating grinding ring l2 has the ability to 45,; float vertically, theoretically transmitting no pressure to the vertical shaft 23. The gear 24 keyed to the shaft 23 meshes with a pinion 25 on a vertical stubshaft 26 which carries a bevel. gear 21. The bevel gear 21 on the vertical stub 50; shaft 26, in turn, meshes with another bevel pinion 28 on a drive shaft 29 so that there is thus obtained a suitable drive through'the medium of the shaft 29 for the vertical shaft 23, and since this particular drive constitutes no special part 5; of the present invention, any other suitable drive being a substitute therefor, it will not be further described other than to say that it, of course, embraces the usual provisions for supporting the gear and shafts on anti-friction bearings.

91 The material to be pulverized may be contained in a hopper 30 located above the pulverizer, and from thishopper the material descends by any convenient means, herein illustrated as the chute 3|, to'a'controllable weighing feeder 3|. The 65- feeder discharges into an inclined chute 3 I entering the top of the pulverizer where the material is discharged onto a conical surface member 32 which is centered with respect to the grinding rings and rows of balls l5 and I6. The conical 705' surface member 32 is carried by the rotatable grinding ring l2 and is provided with an upwardly extending .fin 33 which assists in moving the material to be pulverized beneath the inner row of grinding balls I5, thus preventing a piling up 75. of the material and additionally assisting the centrifugal action in moving the material onto and among the inner row of larger grinding balls I5.

The first stage of pulverization is carried on between the inner row of grinding balls I5 and its complementary grinding race 13, the pressure be- 5 ing adjusted through the medium of the springs l9 exerting their influence upon the grinding ring l1. As before stated the balls l5 are the largest row of balls, and the theory behind this is that these balls by being closer to the center of the pulverizer have exerted upon them less centrifugal action than would otherwise be the case, so that itis of advantage in view of their size and weight tolocate them where they will have as littIe centrifugaI effect as possible and thus the amount of power required to drive the pulverizer is materially diminished. It is also advantageous to have the incoming material meet the larger balls first by reason of the fact that it can more easily enter this ball row due to the spaces be-- tweenthe balls being greater. The larger pieces entering the pulverizer are readily projected between the balls by centrifugal force and the effect of the fin 33, and the large space between the ball and the race surface results in a more effective'pulverization of the larger particles than would be the case with small balls operating upon such large particles. The low centrifugal force atthis p'ointdoes not impart to the heavier. particles such a degree of movement as will remove them from beneath the balls l5 before they are crushed to the .sizeready to be accepted by subsequent stages in which smaller balls are employed I' The materialthus ground under these larger 35 balls is then passed upwardly with increasing velocity by. reason of the larger diameter of the ring I2 with which it comes in contact and is carried beneath the smaller row of balls I8 which roll on' the ball race [4, and which balls have 40;

exerted thereon the downward pressure of the ring I8 occasioned bygravity and the pressure of the springs 20. and is further pulverized, but this subsequent row of small balls has a throttling effect on the amount of material passing through the larger interstices of the large balls so that the pulverizing effect of the first stage is prolonged over, what it would otherwise be. The material is'thusground to a further degree, and on the outeredge of the rotatable grinding ring I2 is tobe' found a ledge gap ring 34 which has an overlapping or overhanging portion, as shown, and which is faced with a wearing material and cooperates with an inwardly extending lateral ledge 35 similarly faced. Between the two there 55, is thus established a ledge gap which may be adjusted by raising and lowering the ring 35 with respect to 'the'iringZ34 through the medium of the screw adjusting devices 35*.

The material which hasbeen'first crushed by the action of the larger balls I 5 and then pulverize'd by the smaller balls i6 'is' held up within the chamber formed above the ledges 34 and 35 sothat a trqttlin'g action also occurs at this point, only such material as .is gradually passed through the gap between the ledges being received into the-next pulverizing stage consisting of the balls 2|"and the stationary ring 22. This throttling effect of the ledge gap serves to retard the progress sufiiciently to insure uniformity of product but at the same time, functions more perfectly than would simply a gap without any overhang, due to the fact that the overhang keeps the materialin the chamber above the ledges 34 and 35 inan agitate'd'condition and soft as contradistinguished from packing that occurs with simply plain rings.

The material which has passed through the row of grinding balls 2|, and thus undergoes a third stage of pulverization under the influence of more than double the pressure on the previous ball elements, works inwardly and falls through the annular opening 36 between the lower grinding ring 22 and the member 31 which is rotating, and is swept out of the pulverizer by the action of the sweeps 39 which in thus sweeping the material from the pulverizer impart centrifugal motion to the material which carries it out through the chute 40.

From the foregoing it will be evident that the materials have moved in a generally radial direction through the pulverizer during the successive stages of pulverization by the two laterally arranged rows of grinding balls, and then downwardly through the throttling ledge gap and inwardly radially of the third stage or row of grinding balls, so that in this third and last stage of pulverization the centrifugal force has a tendency to further retard the motion of the particles through the mill and contributes materially to the fineness of the product.

As illustrated in connections with Fig. 5 the chute 40 passes the pulverized material to a bucket conveyor 4|, which, in turn, lifts the pulverized material to a second chute 42 delivering to a mechanical separator 43 and provided with a hopper bottom M In this mechanical separator the fine material is graded from the coarse and the former conveyed to the hopper bottom 44 whence it may be withdrawn through the chute 45 to a suitable conveying apparatus 46 here illustrated as a Fuller-Kinyon pump. The coarser material is deposited in an inner hopper M and returned through the chute A! to the pulverizer for further treatment.

By this system it is possible to subject the material to a greater number of pulverizing operations than has heretofore been done, and to re.- tard progress of the material through the pulverizer by the natural action of the elements involved,v namely, the trottling of the passage of the material through the larger interstices between the large balls by locating the smaller balls outside of them, as well as centrifugally retarding the larger particles of material for initial pulverization in the zone of lesser centrifugal force; and then to take the material pulverized in these first two stages and further retard it, while keeping the mobile condition by means of a ledge gap which, in combination with the fact that this finer material is fed from the outside inwardly, then utilizing centrifugal force to retard its passage through the third stage of pulverization by causing the material to move in a direction opposite to the direction it tends to take due to the centrifugal effect acquired by its rotation in the ball path, and which thus results in a fine uniform product having a vminimum of coarse particles and pulverized in a device which by reason of its arrangement requires the least grinding pressure to produce the desired result, and this with a minimum of centrifugal effect from the heavy elements during the pulverizing; consequently there is thus effected an arrangement of grinding elements which is such that a minimum of power is re-. quired per unit of weight of material pulverized, and there is also a minimum of chatter, noise and wear.

While, in the foregoing, we have described a specific form of pulverizing apparatus, together with a complete system, it is nevertheless to be understood that in carrying the invention into practice we may resort'to any and all modifications falling within the scope of the appended claims, and that this present embodiment of the pulverizer and system is only one of many pre-' ferred forms which might be disclosed for the purpose of complying with the patent statutes.

We claim:

1. A pulverizer comprising a casing enclosing a rotary grinding ring, a non-rotary grinding ring at one side thereof, concentric inner and outer rows of grinding balls between said grinding rings, said grinding rings being spaced to define a discharge passage at the outer side of said outerrow of balls, means for delivering material to be pulverized to the inner side of said inner row, the inter-ball spaces of said outer row being of smaller size than the inter-ball spaces of said inner row to restrict. the fiow of material between said rows, and means adjacent the periphery of said discharge passage for restricting the flow of material from said outer row of balls.

2. A pulverizer comprising a casing enclosing a rotary grinding ring, a non-rotary grinding ring at one side thereof, concentric inner and outer rows of grinding balls between said grinding rings, said grinding rings being spaced to define'a discharge passage at the outer side of said outer row of balls, means for delivering material to be pulverized to the inner side of said inner row, the balls in said outer row being of smaller size than the balls in said inner row to restrict the flow. of material between said rows, and cooperating adjustable means adjacent the periphery of said discharge passage for restricting the fiow of material from said outer row'of balls.

3. A pulverizer comprising a casing enclosing a rotary grinding ring, a non-rotary grinding ring at one side thereof, concentric inner and outer rows of grinding balls between said grinding rings, means for delivering material to be pulverized to the inner side'ofsaid inner row, the balls in said outer row being of smaller size thanthe balls in saidinner row to restrict the flow of material between said rows, and means forming an adjustable ledge gap between the periphery of said rotary ring and said casing for restricting the flow of material from said outer row to the space between said rotary ring and said casing.

4. A pulverizer comprising a casing enclosing an intermediate rotary grinding ring, upper and lower non-rotary grinding rings at opposite sides thereof, concentric inner and outer rows of grinding balls between said upper and intermediate grindingrings, said upper and intermediate grinding rings being spaced to define a discharge passage at the outer side of said outer row of balls, an orbital row of grinding balls between said lower and intermediate grinding rings, means for delivering material to be pulverized to the inner sideof said upper inner row, the balls in said upper outer row being of smaller size than the balls in said upper inner row to restrict the flow of material between said rows, and means adjacent the periphery of said'disch'arge passage for restricting the flow of material between said upper outer and lower rows.

5. A pulverizer comprising a casing enclosing inner and outer upper concentric rows of grinding balls respectively constituting first and second pulverizing zones having an outward flow of material therethrough, a rotary intermediate grinding ring supporting said inner'and outer ball rows,

inner and outer concentric non-rotary upper grinding rings respectively supported on said inner and outer ball rows, means for exerting independently adjustable grinding pressures on said inner and outer ball rows, said upper and intermediate grinding rings being spaced to define a discharge passage at the outer side of said outer row of balls, a material feed opening in the upper portion of said casing, a rotary table mounted on said intermediate ring and arranged to receive material from said feed opening and to deliver the material to said inner row of balls, a lower nonrotary grinding ring arranged below said outer row of balls, a lowei row of grinding balls positioned between said intermediate and lower grinding rings and constituting a third pulverizing zone receiving material by gravity at its outer side from said second pulverizing zone and having an inward flow of material therethrough, the interball spaces in said upper outer row being of smaller size than the inter-ball spaces in said upper inner row to restrict the flow of material between said first and second pulverizing zones, means adjacent the periphery of said discharge passage for restricting the flow of material between said second and third pulverizing zones, and means mediate grinding rings being spaced to define a discharge passage at the outer side of said outer row of balls, a material feed opening in the upper portion of said casing, a rotary table mounted on said intermediate ring and arranged to're'ceive material from said feed opening and to deliver the material to said inner row of balls, a lower non-rotary grinding ring arranged below said outer row of balls, a lower row of grinding balls positioned between said intermediate and lower grinding rings and constituting a third pulverizing zone receiving material by gravity at its outer side from saidjsecond pulverizing zone and having an inward fiow'of material therethrough;

the balls in said upper outer row being of smaller diameter than the balls in said upper inner row to restrict the fiow of material between said first and second pulverizing zones, means adjacent the periphery of said discharge passage for restricting the flow of material between said second and third pulverizing zones, and means for removing pulverized material leaving the inner side of said lower row of balls. p

' 7. A pulverizer comprising a casing enclosing inner and outer upper concentric rows of grinding balls respectively constituting first and second pulverizing zones havingan outward flow of material therethrough, a rotary intermediate grinding ring supporting said inner and outer ball rows, inner and outer concentric non-rotary upper grinding rings respectively supported on said inner and outer ball rows, means for exerting independently adjustable grinding pressures on said inner and outer ball rows, a material feed open-' ing in the upper portion of said casing, a rotary table mounted on said intermediate ring and arthe balls in said upper outer row being of smaller 1'0 diameter than the balls in said upper inner row to restrict the flow of material between said first and second pulverizing zones, and a rotary sweep for ejecting pulverized material leaving the inner side of said lower row of balls. 15'

8. A pulverizer comprising a stationary casing enclosing an upper circular row of grinding balls constituting an upper pulverizing zone having an outward flow of material therethrough, an intermediate grinding ring supporting said upper row of balls, an upper grinding ring supported on said upper row of balls, means for exerting a grinding pressure on said upper row of balls, a material feed opening in the upper portion of said casing, means on said intermediate ring arranged to re- 25' ceive material from said feed opening and to direct the material into said upper pulverizing zone, a lower grinding ring arranged below said upper row of balls, a lower row of grinding balls positioned between said intermediate and lower 3 grinding rings and constituting a lower pulverizing zone receiving material by gravity from said upper pulverizing zone and having an inward flow of material therethrough, and means forming an adjustable ledge gap between said intermediate ring and said casing for regulating the rate of flow of material between said upper and lower pulverizing zones comprising an annular ledge member mounted on said casing adjacent said intermediate ring, a ring member mounted 40 on said intermediate ring with its outer edge portion superjacent to the inner edge portion of said ledge member and relatively arranged radially so as to effect a reversal in direction of flow of material in passing through the gap therebetween, 45 and means for relatively adjusting said ledge and ring members to vary the size of said gap therebetween.

9. A pulverizer comprising a casing enclosing an upper circular row of grinding balls constitut- 5O ing an upper pulverizing zone having an outward flow of material therethrough, an intermediate grinding ring supporting said upper row of balls, an upper grinding ring supported on said upper row of balls, means for exerting a grinding pressure on said upper row of balls, a material feed opening in the upper portion of said casing, means on said intermediate ring arranged to receive material from said feed opening and to direct the material into said upper pulverizing zone, a lower grinding ring arranged below said upper row of balls, a lower row of grinding balls positioned between said intermediate and lower grinding rings and. constituting a lower pulverizing zone receiving material by gravity from said upper pulverizing zone and having an inward flow of material therethrough, and means forming an adjustable ledge gap between said intermediate ring and said casing for regulating the rate of flow of material between said upper and lower pulverizing zones comprising an annular ledge member adjustably mounted on said casing adjacent said intermediate ring, a ring member mounted on said intermediate ring in overlapping relation to said ledge member, and means for varying the position of said ledge member relative to said ring member to vary the size of said ledge gap.

10. A pulverizer comprising a casing enclosing inner and outer upper concentric rows of grinding balls respectively constituting first and second pulverizing zones having an outward fiow of material therethrough, a rotary intermediate grinding ring supporting said inner and outer ball rows, inner and outer concentric non-rotary upper grinding rings respectively supported on said inner and outer ball rows, means for exerting independently adjustable grinding pressures on said inner and outer ball rows, a material feed opening in the upper portion of said casing, a rotary table mounted on said intermediate ring and arranged to receive material from said feed opening and to deliver the material to said inner row of balls, a lower non-rotary grinding ring arranged below said outer row of balls, a lower row of grinding balls positioned between said intermediate and lower grinding rings and constituting a third pulverizing zone receiving material by gravity as its outer side from said second pulverizing zone and having an inward flow of material therethrough, the balls in said upper outer row being of smaller diameter than the balls in said upper inner row to restrict the flow of material between said first and second pulverizing zones, means forming an adjustable ledge gap between the periphery of said intermediate ring and said casing for regulating the rate of flow of material between said second and third pulverizing zones, and a rotary sweep for ejecting pulverized material leaving the inner side of said lower row of balls.

11. A pulverizer comprising a plurality of relatively movable parts constituting an upper pulverizing zone, a plurality of relatively movable grinding parts constituting a lower pulverizing zone receiving material from said upper pulverizing zone, and means for regulating the rate of fiow of material between said upper and lower pulverizing zones comprising a plurality of plate members mounted respectively on a movable grinding part and a stationary part, the plate member on the movable grinding part being superjacent the plate on the stationary part, said plates being relatively arranged so as to effect a reversal in direction of flow of material in passing through the gap therebetween, and means for relatively adjusting said plate members to vary the size of said gap therebetween.

12. A pulverizer comprising a casing enclosing a plurality of relatively movable parts constituting an upper pulverizing zone having an outward flow of material therethrough, a plurality of relatively movable grinding parts constituting a lower pulverizing zone receiving material by gravity from said upper pulverizing zone and having an inward flow of material therethrough, means for regulating the rate of flow of material between said upper and lower pulverizing zones comprising an annular ledge member mounted on said casing, and a ring member mounted on an adjacent rotary grinding part in overlapping relation to said ledge member.

13. A pulverizer comprising a casing enclosing a plurality of relatively movable parts constituting an upper pulverizing zone having an outward flow of material therethrough, a plurality of relatively movable grinding parts constituting a lower pulverizing zone receiving material by gravity from said upper pulverizing zone and having an inward flow of material therethrough, means for regulating the rate of flow of material between said upper and lower pulverizing zones comprising an annular ledge member mounted on said casing, a ring member mounted on an adjacent rotary grinding part in overlapping relation to said ledge member, and means for relatively adjusting said ledge and ring members tovary the size of the gap therebetween.

14. A pulverizer comprising a stationary casing enclosing an upper circular row of rolling grinding elements, an intermediate grinding ring supporting said upper row of grinding elements, an upper grinding ring supported on said upper row of grinding elements, a lower grinding ring, a lower circular row of rolling grinding elements positioned between said intermediate and lower grinding rings, and means forming a ledge gap between said intermediate ring and said casing for regulating the rate of, flow of material between said upper and lower rows of grinding elements comprising an annular ledge member mounted on said casing adjacent said intermediate ring, and a ring member mounted on said intermediate ring with its outer edge portion superjacent to the inner edge portion of said ledge member and relatively arranged radially so as to eflect a reversal in direction of flow of material in passing through the gap therebetween.

15. A pulverizer comprising an upper circular row of rolling grinding elements constituting an upper pulverizing zone having a flow of material therethrough in one direction, an intermediate grinding ring supporting said upper row of grinding elements, an upper grinding ring supported on said upper row of grinding elements, a lower grinding ring, a lower row of rolling grinding elements positioned between said intermediate and lower grinding rings and constituting a lower pulverizing zone receiving material from said upper pulverizing zone and having a flow of material therethrough in the opposite direction, and means for regulating the rate of flow of material between said upper and lower pulverizing zones comprising a pair of circular plate members arranged in overlapping relation, and means for relatively adjusting said plate members to vary the size of the gap therebetween.

16. A pulverizer comprising a casing enclosing an upper circular row of. rolling grinding elements constituting an upper pulverizing zone having an outward flow of material therethrough, a rotary intermediate grinding ring supporting said upper row of grinding elements, an upper nonrotary grinding ring supported on said upper row of grinding elements, a lower non-rotary grinding ring, a lower row of rolling grinding elements positioned between said intermediate and lower grinding rings and constituting a lower pulverizing zone receiving material by gravity from said upper pulverizing zone and having an inward flow of material therethrough, and means forming an adjustable ledge gap between said intermediate ring and said casing for regulating the rate of flow of material between said upper and lower pulverizing zones comprising an annular ledge member mounted on said casing adjacent said intermediate ring, a ring member mounted on said intermediate ring in overlapping relation to said ledge member, and means for relatively adjusting said ledge and ring members to vary the size of said ledge gap.

ERVIN G. BAILEY. PERRY R. CASSIDY. RALPH M. HARDGROVE. 

